Grinding- btjrk



J. H. LETZ GRINDING BURR May 1-3 1924;

Original Filed Jan. 14. 1920 Patented ay 13, 1924.

JOHN HOLLAND LETZ, OLE CROWN POINT, INDIANA.

GRINDING Bonn.

' Application filed. January 14, 1920, Serial No. 351,361. Renewed January 28, 1 924,.

To all win-m) it may concern:

Be it known that I, JOHN HOLLAND Ln'rz,

a citizen of'the UnitedStates, and a resident of Crown Point, in the county of Lake and State of Indiana, have invented certain new and useful Improvements in Grinding Burrs, of which the following is a full, clear, and exact specification.

' My invention is concerned with grinding burrs of the class shown in my Patent 1,244,516, dated October 30, 1917, in which the base has a flat annular portion upon which are formed outwardly extending ribs which have their tops ground 'ofi' fiat to present shearing edges to co operate with similarly formed shearing edges on the opposed burr, and is designed to produce a burr having a novel design and arrange, ment of the ribs so that it will grind satisfactorily such diverse articles as corn, oats, beans, short hay, etc, and will have a longer life and operate more satisfactorily than one having the ribs designed as in my aforesaid patent. To illustrate my invention, I annex hereto a sheet of drawings in which the same reference characters are used to designate identical partsin all the figures, of which- Fig. 1 is a plan view of a portion of a burr embodying my invention;

Fig. 2 is a central section on a reduced scale; and

Fig. 3 is a section on the line 3-3 of Fig. 1. 1

The base A is an annulus preferably a metal casting having the design in cross section as it appears in Fig. 3, with the inclined, depressed annular portion B sur rounding the circular feeding opening, and the customary pair of annular ribs C and D on the back.

The grinding ribs are preferably arranged in similar sections, as shown, with eachsection occupying one-sixth of the faceof the burr. At the beginning of each sectionis a main rib E extending inward slightly be yond the inner edge of the annulus, as shown, and outward substantially at the angle shown to a radial line intersecting it, say one-half of the distance across the annulus, where it preferably has the short defleeting end 6 turned oil at a greater angle to a radial line. The pair of these main ribs E bounding any section serve to guide the material into said section.

or shearing ribs.

In each section parallel to the main rib E are a plurality of ribs F, F, F F F F F F F F F, F, arranged inthree parallel rows, similar parallel ribs G, G, G and G pan allel to the other three rows but with the ribsG, G, G", and G not strictly parallel-to the ribs of the first three rows. Each' of the ribs F, etc, and G, etc., consists of a straight body portionwith preferably the deflecting ends fand g,'although it will be understood thatsome of these ribs are mutilated and incomplete in their design because of their running into the perimeter of the burr. In addition to the aforesaid sets of ribs, I provide three somewhat similar ribs H, .H' and H parallel in their general outlines to .they ribs .of the rows of which they constitute the inner ends, but they, like the main ribs E, have their bases thickened to give additional substance and body to the ribs, as the wear from the grinding action is greatest on the inner and there is another row of portion .of the burrs. In the row with the rib IF, I may placethe shortened ribs H H H H H H which constitute a sort of an aborted row back of the main rib E of the next section. All of the ribs so far described are cast so that their com-. plete upper surface is'ground off flat when the burr is dressed, and their entire advancing edges can have a shearing action if the material is against them when they meet the shearing edges of the opposed burr.

If the ribs so far described only were used, the material would pass across the face of the burrs toorapidly and it would not be properly ground. In myprior Pat: ent, No. 1,244,516 before referred to, to prevent this I placed lower intercepting ribs there marked. M, etc., N, etc., 0, etc, and P, etc., between the outer ends of the shearing ribs, and extending directly across'the channel formed between the aforesaid main 1/ low intercepting. ribswearout too rapidly, with the result that the burrs are soon gr1nd ing much more coarsely than is intended,

. I have found that these and for that reason in my present burr, I

havev substituted for these intercepting or bafiie jribs M, etc, N, etc.,,O, etc, andP, etc, of the old patent, the pairs of combined intercepting and grinding ribs L, which, as seen, have the angle, in the outer ends to make their design conform to that of the adjacent grinding ribs, but their inner ends, instead of having their top: surfaces flush with the. top surfaces of" the shearing ribs as are the top surfaces of the outer ends, are tapered down, preferably to a point where they reachthe surface of the plate. The action of these intercepting ribs Ltherefore is to slow up the passage of the material. passing outward, if it is already ground fine enough to pass through the narrow channels remaining, but if it is too coarse to do so, it is forced up by the tapered: inner ends to a. level where it will be subjected to the aetionof the shearing edges and thus ground finer;- These intercepting ribs present. a much greater wearing. surface tothe grain than did the ribs M, etc, N, etc, 0, etc, and P, etc, of my aforesaid patent, so that they produce. a longer lived burr as. well as one that grinds more effectively.

As the tendency of the rotation. of the burr is to throw the material being ground generally toward the left, in order to spread it out over the entire surface between the adjacent shearing ribs, such as F and. F for example, I place between: each such pair of ribs and. near the inner ends of the intercepting ribs L, the deflecting ribs M, which ribs are set at an angle to the line of the grinding. ribs so that the material contacting therewith tends to be deflected to the right, thus counterbalancing the tendency of the material to go to the left, and thus distributing it better. As some of the material, especially if" it is ground fine enough, should be permitted to follow the natural trend to the left, I bevel off, down to the lower surface of the plate. the inner ends of the ribs M, the outer ends of which have their top surfaces flush. with those of the grinding ribs.-

Extending generally inward from each of the deflecting ribs M will be noted the spaces N which have no teeth on them. These are provided to give room for elongated pieces of material, such as oat grains, to turn freely to get their longitudinal axes in alignment with the paths between the channels, and thus facilitate an even flow of the material between the burrs.

From the foregoing description of the construction and function of the various ribs, it is thought that the operation of the burr will be readily understoodwithout any further description. At the outer edge, any spaces which would otherwise be vacant are filled by the short ribs, such as 0', to prevent the premature escape of the material from the burrs.

lVhile I have shown and described my invention as embodied in the form which I at present consider best adapted to carry out its purposes, it will. be understood that it is capable of modification, and that I do not desire to be limited in the interpretation. of. the following claims except as may be necessitated by thestate. of the prior art.

What I claim as new and desire to secure by Letters Patent of the United States is- 1'. A grinding plate-having on its surface plural series of long shearing ribs with their'ground off tops in the same horizontal plane and arranged to form generally parallel passages set at a considerable angle to radial lines, together with plural series: of short ballie ribs between the outer ends of the shearing ribs but not connected thereto and extending in a generally parallel direction to said outer ends, said shearing and battle ribs being closely spaced so as toform narrow parallel channels for the ground material below the shearing ribs.

2; A grinding plate having, on its surface plural series of long shearing ribs with their ground off topsvin the same horizontal plane and arranged to form generally parallel passages set at a considerable anglev to radial lines, together with plural series of short bafiie ribs between the outer ends of the shearing. ribs but not, connected thereto and. extending in a generally parallel direction to said outer ends, said baffle ribs having their inner ends tapered down from the shearing level to. the body of the plate and pointing toward the material coming from the center of the plate.

3. A grinding plate having on its surface plural series of long shearing ribs with their ground off tops in the same horizontal plane and arranged to form generally parallel passages set at a considerable angle to radial lines, together with shorter deflecting ribs set between the shearing ribs toward the inner ends thereof but not connected thereto and extending at such an angle thereto that their inner surfaces tend to throw the material being ground toward the direction the plate is rotating.

4.. A grinding plate having onv its surface plural series of long shearing ribs with their groimd ofi' tops in the same horizontal plane and arranged to form generally parallel passages set at a considerable angle to radial lines, together with shorter deflecting ribs set between the shearing ribs but not connected thereto and extending at such an angle thereto that their inner surfaces tend: tothrow the material. being ground toward the direction the plate is rotating. said deflecting ribs having their inner ends tapered do-wn from the shearing level to the body of the plate and pointing substantially toward the center of the plate.

5. A grinding plate having on its surfaceplural series of long shearing ribs with their ground off tops in the same horizontal plane and arranged to form generally par allel passages set at a considerable angle to radial lines, together with plural series of short baflie ribs between the outer ends of the shearing ribs and extending in a generally parallel direction to said outer ends, and shorter deflecting ribs set between the shearing ribs adjacent the inner ends of the baffle ribs and extending at such an angle to the shearing ribs that their inner surfaces tend to throw the material being ground toward the direction the plate is rotating,

said bafil-e and deflecting ribs having their 10 inner ends tapered down from the shearing level'tothe body of the plate.

In witness whereof, I have hereunto set my hand and afiixed my seal, this 18th day of December, A. D. 1919.

JOHN HOLLAND LETZ. [1 s.]

lVitness: I

JOHN HOWARD MoELnoY. 

